Traditional absorbent systems for personal care products store substantially all liquid insults in the crotch region. This results in the crotch region being heavily loaded with liquid by the first insult and can result in insufficient capacity for a second, third or later insult. This crotch area loading can cause the product to sag away from the wearer, causing discomfort for the wearer and creating the possibility of leakage. The storage of insults in the crotch region also requires that the crotch region be wider than would be possible in a system that stored insults in a different location. A wider crotch area also causes discomfort to the wearer. Further, storage in the crotch area does not use the entire product area for storage, resulting in waste of absorbent material which is usually spread throughout the product area. Storage primarily in the crotch area would, therefore, raise product cost through the inefficient use of materials.
A system in which an insult would be accepted by a personal care product and distributed to remote areas of the product for storage away from the crotch area so that the crotch area of the product could be free to accept another insult, would be preferable to the crotch area storage design. In this context, the location of the fluid after an insult is referred to as the fill patter. The fill patter has a relationship to other desirable absorbent product attributes such as leakage levels from the product, ability to achieve low leakage with a narrow crotch, fit and therefore comfort to the wearer, and visual aesthetics, as noted above. A remote storage system could maximize the use of the area of the product, reduce sag and allow the production of a personal care product with a narrower, more comfortable crotch. A more efficient use of product materials should result in a lower consumer cost.
It is therefore an object of this invention to provide a personal care product having an absorbent system which may be filled in a particular order such that the insult liquid is moved to remote storage locations. Such a structure will intake a liquid insult from the wearer and move the liquid to a remote storage location in a predetermined progression and pattern of fill. It is a further object of the invention to provide personal care products with narrow crotch designs as well as personal care product designs with specific liquid storage locations.
The objects of this invention are achieved by an absorbent system having the functions of intake, controlled release, distribution, transfer and final storage and a bodyside liner, a surge layer, a multifunctional material, a distribution layer and a retention layer which are in sufficient contact to transfer liquid between them. The surge layer is capable of handling an incoming liquid insult of between about 60 and 100 cc at a volumetric flow rate of from about 5 to 20 cc/sec and has a capillary tension. The multifunctional material has a permeability between about 100 and 10000 Darcys, a capillary tension higher than the surge layer and between about 2 and 15 cm, and a runoff rate of less than 25 ml per 100 ml insult over a life of three insults of 100 ml each separated by 30 minutes. The distribution layer has a capillary tension higher than the capillary tension of the surge layer and an equilibrium wicking height capillary tension of at least about 15 cm as measured by the wicking of an 8.5 g/l saline solution according to the Vertical Wicking Flux Rate Test throughout the life cycle of the absorbent system. The retention layer absorbs liquid quickly and efficiently from the distribution layer in a controlled manner such that liquid maybe stored in a desired pattern. The retention layer also has a capillary tension higher than the capillary tension of the distribution layer throughout the life cycle of the absorbent system and is mechanically stabilized. The absorbent system is divided transversely into a center zone adjacent two intermediate zones which are each adjacent an end zone. The zones are about equally sized. A ratio of an amount of liquid stored in the center zone to an amount of liquid stored in at least one of the end zones 30 minutes after each of three insults of 80 ml according to a MIST Evaluation Test defines a fill ratio of the absorbent system which must be less than 5:1. Finally, the absorbent system has a fully saturated capacity of less than 450 g.